The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A wafer support assembly such as a pedestal for semiconductor processing is disposed in a semiconductor processing chamber and typically includes a wafer support portion and a shaft secured to a central region of the wafer support portion. The wafer support portion may include a resistive layer having a resistive heating element for generating heat and electric terminations for connecting the resistive heating elements to an external power source. The electric terminations are disposed adjacent to the central region of the wafer support portion and extend in the shaft. Typically, when integrating more than one resistive layer, a routing layer and vias or interconnects are used to interconnect and terminate the heater circuits in the central region of the wafer support portion.
Top and bottom layers of the wafer support portion are bonded together for example by diffusion bonding or assisted hot press sintering. This high-pressure, low-strain process forms a powder or compacted powder at a high enough temperature to induce sintering in order to form a high-density component/compact. Typically, the compacted powder is put into a mold and high temperatures and pressure are applied for densification and sintering. The mold is made of a material that can withstand the high temperatures and pressures, such as for example, graphite.
Challenges associated with integrated vias or interconnects during hot press sintering include induced stresses due to shrinkage of ceramic, uncontrollable and unpredicted displacements, high plastic deformation, and failure and fracturing of the electrically conductive vias. Another issue is interaction of the vias and ceramic material during hot press sintering process with carbon that is emitted from graphite molds. These challenges, among other challenges in the use of ceramic pedestals in semiconductor processing are addressed by the present disclosure.